Conventionally, a refrigeration apparatus that cools interior air of a refrigerator unit or freezer unit has been known. For example, Patent Document 1 discloses a refrigeration apparatus that cools interior air of a container used in marine transport or the like. The refrigeration apparatus includes a refrigerant circuit to which a compressor, a condenser, an expansion valve, and a cooling heat exchanger (evaporator) are connected. The refrigeration apparatus circulates a refrigerant in the refrigerant circuit to perform a vapor-compression refrigeration cycle. As a result, the refrigerant flowing in the cooling heat exchanger absorbs heat from interior air and evaporates to cool the interior air.
In the refrigeration apparatus described above, temperature control with high precision is required such that interior air is, for example, approximately ±0.5° C. with respect to a target temperature in accordance with a cargo or the like within the container. Therefore, in the refrigeration apparatus described above, the compressor is operated, always giving priority to ensuring precision of the temperature control. However, once interior air is cooled within the container, cooling load does not change drastically. Also, it is unlikely that the external temperature that gives influence on the cooling load changes drastically. Thus, as disclosed in Patent Document 2, for example, a refrigeration apparatus provided with a power-saving operation mode in which a compressor is operated intermittently has been proposed.
In the refrigeration apparatuses shown in the Patent Documents 1 and 2, a dehumidification operation in which the humidity of interior air is adjusted is often performed when the humidity of interior air that is a cooling target needs to be held within a certain range. However, in the case of performing the dehumidification operation, it is necessary to perform a continuous operation of a compressor in the refrigeration apparatus in order to ensure the operation performance for both dehumidification and cooling. Thus, power consumption of the refrigeration apparatus increases. Therefore, although provided with the power-saving operation mode, the refrigeration apparatus is not sufficient in power efficiency. Thus, further improvement in power efficiency has been desired.
Patent Document 1: Japanese Patent Application Laid-open No. 2002-327964
Patent Document 2: Japanese Patent No. 3864989